Silicone rubbers have been widely used in diverse applications for heat resistance, low-temperature resistance, and electrical properties. They are processed by any desired one of the various conventional methods depending on a particular application. In general, silicone rubbers exhibit poor mold release characteristics. Typically, silicone rubber is pressure molded and vulcanized in a metal mold and then removed from the mold. The molded silicone rubber article often fails upon mold parting due to poor mold release characteristics.
For ease of removal of molded parts from the mold, various attempts including plating of chromium and coating of Teflon resin to the surface of the metal mold have been made with less satisfactory results. It is also known to apply lubricants such as surface active agents, halocarbon polymers and talc to the metal mold. This technique, however, is undesirable because of complexity added to the overall process since the lubricant coatings do not last and repetitive applications are necessary and because of the adverse influence on the quality of molded parts. Further it is proposed to add metal carboxylates to silicone rubber compositions for improving mold release characteristics as disclosed in U.S. Pat. No. 3,549,744 and Japanese Patent Publication No. 45099/1980. Undesirable compression set is left in the resulting silicone rubber and the addition of a substantial amount of metal carboxylate gives rise to a safety problem. In addition, mold release is improved to only a limited extent.
The silicone rubber has another drawback in that since organopolysiloxanes have low intermolecular forces, their compositions are limp and easy to masticate, but do not smoothly separate from the rolls resulting in inefficient operations. As solutions to this problem it has been proposed, for example, to add higher fatty acid metal salts as disclosed in Japanese Patent Publication No. 19951/1980, to add higher fatty acids as disclosed in Japanese Patent Application Kokai No. 44655/1982, and to add fatty acids or esters, metal salts or amides thereof along with polytetrafluoroethylene as disclosed in Japanese Patent Application Kokai Nos. 27749/1983 and 194949/1983. Mold release is not satisfactory in some attempts and some adversely affect heat resistance.
In turn, conductor wires are prepared by extrusion molding silicone rubber on a copper or tin-plated copper core conductor. Undesirably, the silicone rubber is closely bonded to the core conductor as time goes by at elevated temperatures. One known solution to this problem is to add fatty acids or fatty acid metal salts as disclosed in Japanese Patent Application Kokai Nos. 159850/1982 and 159851/1982. This solution, however, is not satisfactory in preventing the silicone rubber coating from bonding to the core conductor at elevated temperatures in excess of 200.degree. C.
Also, silicone rubber is used in contact with glass. The silicone rubber is closely bonded to glass with the lapse of time. If one attempts to separate them, the silicone rubber would fail or part of the silicone rubber is left attached to the glass surface.